P2516
DTC P151C or P2516-P2518
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P151C
- Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Not Plausible
DTC P2516
- Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Performance
DTC P2517
- Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Circuit Low Voltage
DTC P2518
- Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Circuit High Voltage
Circuit/System Description
The Hybrid Powertrain control module (HPCM2) monitors the low side refrigerant pressure through the A/C refrigerant pressure sensor. The HPCM2 supplies a 5 V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the sensor signal to the HPCM2 to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is too high or too low, the HPCM2 will not allow the activation of the A/C compressor.
To make the P151C Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Not Plausible DTC evaluation, the HPCM2 compares the A/C Low Side Refrigerant Pressure Sensor reading with the A/C high side refrigerant pressure reading after a dormant soak period.
In addition, to make the P151C Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Not Plausible DTC evaluation, the HPCM2 also uses the A/C temperature sensor 2 reading.
These two sensors are both in the same environment. The HPCM2 compares the values of these sensors after a dormant soak period. The HPCM2 takes the temperature value and calculates an equivalent pressure for gaseous R134a at that temperature and at the pressure as reported by the Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor and compares these.
DTC P151C sets if both of these comparisons show that the A/C Low Side Refrigerant Pressor Sensor is not in agreement with the other sensors.
To make the DTC P2516 Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor evaluation, the HPCM2 looks for a drop in the pressure value after the compressor has run for a short period after a dormant soak period.
Conditions for Running the DTC
P151C
* System voltage above 9V.
* HPCM2 is awake and communicating.
* None of these DTCs may be active: P2517, P2518, P0073; P0072; P0071, P0119; P0118; P0117; P0116, P0531, P0532; P0533, P537,P538, P153B, P0606
* Outside Air Temperature raw and corrected values must have had a chance to settle out. Once this occurs these variables are assigned a status of valid. May need to have some time driving in EV mode
* Engine coolant temperature must be within 15C degrees of outside air temperature
* Outside Air Temperature between 0C and +25C.
* AC compressor must have been off for an hour since the last time the AC compressor was on.
P2516
* System voltage above 9V.
* HPCM2 is awake and communicating.
* None of these DTCs may be active: P2517, P2518, P0073; P0072; P0071, P0119; P0118; P0117; P0116, P0606
* Engine coolant temperature must be within 15C degrees of outside air temperature
* AC compressor must have been off for an hour since the last time the AC compressor was on.
* AC compressor must be turned on for one minute. (This may the require the service technician to select an HVAC mode that causes the AC compressor to run).
P2517 or P2518
* System voltage above 9V.
* HPCM2 is awake and communicating.
Conditions for Setting the DTC
DTC P151C
The A/C low side Refrigerant Pressure reading and the A/C high side Refrigerant Pressure reading must be within 200 KPa. and the A/C low side Refrigerant Pressure reading and the the pressure derived from the A/C Refrigerant Temperature Sensor 2 must be within 200KPa
DTC P2516
The difference between the A/C low side Refrigerant pressure Sensor before compressor on and after compressor on changes less than 50KPa over a 15 second period.
DTC P2517
The HPCM2 detects a short to ground or open at the low side A/C pressure sensor signal circuit.
DTC P2518
The HPCM2 detects a short to voltage at the low side A/C pressure sensor signal circuit.
Action Taken When the DTC Sets
These are type B DTCs.
Conditions for Clearing the DTC
These are type B DTCs.
Reference Information
Schematic Reference
HVAC Schematics HVAC - Automatic
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation
Automatic HVAC Description and Operation HVAC - Automatic
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Diagnostic Aids
Because the 5V voltage references inside the HPCM2 are used by more than one sensor, when a circuit high fault DTC sets (P2518), the following DTCs may also set: P0606, P26A7 and P0CE7. If all four DTCs in this service procedure are set, P2518 and P0606 should be diagnosed before P26A7 or P0CE7
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B18 Low Side A/C Refrigerant Pressure Sensor.
2. Ignition ON, test for 4.8-5.2V between the 5V reference circuit terminal 2 and ground.
• If less than the specified range, test the 5V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HPCM2.
• If greater than the specified range, test the 5V reference circuit for a short to voltage. If the circuit tests normal, replace the HPCM2.
3. Test for 4.8-5.2V between the 5V reference circuit terminal 2 and the low reference circuit terminal 1.
• If less than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HPCM2.
• If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the HPCM2.
4. Verify the scan tool A/C Low Side Pressure Sensor parameter is less than 0.3V.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HPCM2.
5. Install a 3A fused jumper wire between the following signal circuit terminal 3 and the 5V reference circuit terminal 2. Verify the scan tool A/C low side pressure sensor parameter is greater than 4.8V.
• If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the HPCM2.
6. If all circuits test normal, replace the B18 A/C Low Side Refrigerant Pressure Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* HVAC Component Replacement Reference HVAC Component Replacement Reference
* Control Module References Control Module References